This invention relates to an electric push-button switch of the kind comprising, in a hollow body carrying two contact terminals normally insulated from one another, a connection means controlled by a push-button and mounted for axial movement in the body between a disconnected position of rest, in which the connection means is at a distance from the contact terminals, and a connected working position in which the connection means is in contact with each of the contact terminals and makes an electrical connection between them; resilient return means urging the connection means in the direction of its position of rest, and cam means disposed between the body and the connection means for the purpose of determining the position of rest and the working position of the connection means and the controlled movement of the connection means from one of these positions to the other, the said cam means comprising a catch pin and a guide plate adapted to co-operate with the catch pin and carrying, on the one hand, two axially spaced retaining notches and, on the other hand, two oblique displacement paths on the axis of movement of the connection means in the body, for the directed passage of the catch pin from one of the said retaining notches to the other.
It relates more particularly, but not exclusively, to electric switches of this kind which, being intended to equip the instrument panels of automobile vehicles for the controlled operation of any accessory at the disposal of the driver, have to be individually provided with two distinct lighting means, namely a first relatively low power lighting means brought into operation as soon as natural lighting becomes insufficient and the driver of the vehicle lights up the side lights of the latter, this first lighting means serving for the individual location of the various switches provided on the instrument panel of the vehicle, and a second lighting means brought into operation only when the accessory controlled by a switch of the said kind is actually in operation, for the purpose of the controlled location of those accessories which have thus actually been brought into operation.
In a general way, in electric switches of this kind, the catch pin or stud permitting the securing of the position of rest and working position of the connection means by co-operation with a guide plate forming a cam, generally of the heartcam type, is mounted for free movement in a channel.
Consequently, depending on the direction imparted to a switch of this kind, the aforesaid catch pin or stud is adapted to fall to the bottom of the channel in which it is disposed, when this channel becomes vertical.
As a result, during the manipulations to which a switch of this kind is subjected when being packed and/or fitted in its position of use, the catch pin or stud may be incorrectly positioned in relation to the guide plate with which it is associated, thus leading subsequently to defective operation of the unit.
Furthermore, in cases where, as indicated above, it is necessary to equip a switch of this kind with two separate lighting systems, the two lighting systems are generally provided by a single lamp with which there are associated two supply circuits of different resistivities, of which one, having the higher resistivity, is systematically operated when the driver of the vehicle lights up the lights of the vehicle, and the other, which has lower resistivity, is operated only when the accessory controlled by the switch in question is actually operated.
Because of its nature, this arrangement nevertheless requires the use of two different resistive circuits and is therefore relatively expensive.
Furthermore, although it actually makes it possible to distinguish between the two lighting systems proposed, this distinction is made only through the different intensities of the lighting systems and not, as may be desirable, by different colorations of the lighting systems.
It is an object of the present invention to overcome these difficulties.
More precisely, it is an object to provide an electric push-button switch of the kind first mentioned above which has great operating reliability and is capable of being equipped with means making it possible to provide two lighting systems which are distinct both in respect of intensity and in respect of coloration.
According to the invention there is provided an electric push-button switch of the kind first described above wherein the guide plate is rigidly fastened to the connection means and the catch pin which co-operates therewith forms an independent element which passes entirely through the wall of the body situated opposite the guide plate carried by the connection means, with the aid of a hole provided for the purpose in the said wall, and wherein the independent element is subjected to the action of resilient means urging it in the direction of the guide plate with which it cooperates.
In this way the catch pin is permanently held in the correct position by friction against the guide plate with which it cooperates.
It has already been proposed to subject a catch pin of this kind to the action of resilient means.
However, in arrangements proposed hitherto in this respect a catch pin of this kind is not mounted for movement in a hole; these known arrangements relate simply to a pin mounted for swivel-joint rocking on the spot, and the resilient means associated with it simply serve to return it to a middle position of rest.
In the arrangement according to the present invention the resilient means should not offer resistance to the displacement of the catch pin, on which it acts, along the hole in which the pin is disposed.
At the end of the body opposite to that where the push-button is disposed the body of the switch may be formed by a removable end carrying, around a lamp support, a tubular case extending substantially axially in the body in the direction of the push-button, and at least a part of the body may be provided with portions permitting the passage of light, which are for example formed by transparent or at least translucent zones of the wall of the body and/or by apertures provided for that purpose in the said wall.
When the body of the switch has portions permitting the passage of light, it permits the transmission in the direction of the push-button of the ambient light in which it is itself situated, this ambient light being brought into action, as is usual per se, as soon as the lights of the vehicle fitted with the switch are lit up.
When the accessory controlled by the electric switch is actually in operation the lamp with which the switch is equipped is in turn lit up and its own illumination is superimposed on that resulting from the ambient illumination.
The two corresponding illuminations are therefore distinguished in intensity; they may in addition have different colorations, for which purpose a coloured screen may advantageously be carried by the tubular casing surrounding the lamp holder.
The tubular casing is preferably, but not necessarily, opaque so that when the lamp surrounding it is illuminated the lighting of the lamp does not interfere unduly with the ambient light and therefore does not modify the latter.
Furthermore, when it is opaque in this manner the tubular case advantageously channels in the direction of the push-button the illumination provided by the lamp which it surrounds, thus preventing the dispersion of this lighting which might attenuate its intensity at the practical level of the push-button.
However, this may be, and in accordance with arrangements known per se, both of the two illuminations provided for the electric switch of the invention can, for example, act in practice either through the actual push-button controlling the switch, for which purpose the push-button is made at least partly translucent, or around the push-button, for which purpose the body of the switch is itself provided with a translucent annular zone around the push-button.